Keepout margin : This the one of the technique using during placement macros and standard cells in the core area. It is the region around the boundary of fixed cells in a block in which no other cells are placed. The width of the keep-out margin on each side of the fixed cell can be the same or different. Keeping the placement of cells, macros etc.. This technique can avoids congestion and nets detouring and timings. For the best quality of results. How we decide the margin? The margin is decided based on the macros or IPs .These macros and IPs will come from vendors its clearly mention in the document regarding the margin around the macros like expected values will be mentioned, by reading the document we can get the values will giving the values we may increase or decrease depend on the problem we faced in the core area. For the std cells, basically we will keep out margin to mainly for AOI ,IOA and Multibit flops etc. Why only AOI, IOA and multibit flops because th...
AOCV (ADVANCE ON_CHIP_VARITIONS) Aocv will be calculated with the depth and distance by seeing above figure you will get an idea. for the above figure we will consider depth as 6 because path-1 is the longest path from the above fig. so tool will take the depth as 6 from the aocv file and distance is calculated with the help of will the diagonal distance. But AOCV will be calculated from the diverging point only. Note: just understanding purpose I kept buffer in the above diagram in place of buffers it may gates flops etc.. AOCV setting can be done on both PNR tools and STA tools. While doing analysis we will flow some time Graph based Analysis and Path based Analysis both With the help of AOCV we will get 3 to 4% of pessimism lets see some difference between GBA and PBA GBA it will have worst skew (transitions) its not realistic fast analyzer less memory required worst aocv derating will occurs.. etc PBA Actual skew will be propagated i...
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